1. Field of the Invention
The present invention relates to a shield casing which covers an electronic component mounted on a circuit board and an electronic apparatus including the shield casing.
2. Related Art
An example of an electronic apparatus, such as a mobile phone, includes a circuit board on which electronic components are mounted and which is accommodated in a housing. The electronic components mounted on the circuit board include, for example, a high-frequency circuit component for radio communication, which is easily influenced by noise like electromagnetic waves. The electronic component which is easily influenced by noise is generally covered with a shield casing for shielding the electronic component from noise.
An example of a known shield casing is a two-piece shield casing which includes a principal-plane member and side walls which are formed separately from the principal-plane member. The side walls form a frame body, and the principal-plane member forms a lid body. The two-piece shield casing is formed by fitting the lid body to the frame body.
In a two-piece shield casing, the frame body is first fixed to a mounting surface of the circuit board, for example, such that the frame body surrounds the electronic component. The lid body is subsequently fitted to the frame body so as to fix the shield casing to the circuit board.
In the two-piece shield casing, when the lid body is fitted to the frame body, side walls of the lid body expand outward in a planar direction of the principal-plane member of the lid body, that is, in a direction substantially perpendicular to the direction in which the lid body is fitted to the frame body. Therefore, it is necessary to prevent the lid body from being separated from the frame body after the lid body is fitted to the frame body. However, plastic deformation of the side walls of the lid body easily occurs while the side walls expand outward in the planar direction of the principal-plane member.
Therefore, there has been a demand for a shield casing that does not easily cause plastic deformation.